.box{
    width: 80%;
    height: 100px;
    margin: 0 auto;
    border: 2px solid red;
    background: aquamarine;
}

 /* 静态定位 */
.pos_static{
    position: static;
    background: yellowgreen;
}

/* 相对定位 */
.pos_relative{
    position: relative;
    background: green;
    top: 20px;
    left: 20px;
    z-index: -1;
}

/* 绝对定位 */
.pos_absolute{
    position: absolute;
    z-index:  1;
    background: cornflowerblue;
    top: 20px;
    left: 20px;
}

.parent_absolute{
    position: relative;
    /* position: absolute; */
}

.pos_fixed{
    position: fixed;
    background: firebrick;
    width: 64px;
    height: 64px;
    right: 16px;
    bottom: 64px;
}

.pos_sticky{
    position: sticky;
    background: gold;
    top: 0;
}